The present invention relates to a novel bioactive peptide derived from brain hypothalami, testes or the like, a DNA containing a DNA segment coding for the peptide, a transformant bearing the DNA, and a method for preparing the above peptide by using the transformant.
Various hormones secreted by brain hypothalami and hypophyses have been known. Examples thereof include thyrotropin releasing hormone, luteinizing hormone releasing hormone, somatostatin, adrenocorticotropic hormone, growth hormone and prolactin. Action thereof has been well studied. One of the present inventors studied a certain novel bioactive substance of hypothalamic origin other than these hormones based upon adenylate cyclase activity, and consequently discovered a peptide consisting of 38 amino acid residues, which had not been reported till then. The structure thereof was determined and the peptide was named "PACAP38".
The present inventors filed applications for patents (Japanese Patent Application Nos. 1-155791/1990 and 1-284771/1990) on cDNA of sheep PACAP38, and an application for a patent (Japanese Patent Application No. 1-259924/1990) on the partial structure of cDNA of human PACAP38. It was also discovered that the amino acid sequence of the mature portion of sheep PACAP38 was the same as that of human PACAP38, and that some amino acids of the precursors thereof were substituted.
However, although the existence of the PACAP38 peptides was confirmed as described above, it is difficult to isolate and purify the peptides and their precursors from hypothalami or the like, because of the necessity of very complicated operations, and that the desired peptides are obtained only in small amounts. It has therefore been desired to provide a method for obtaining the peptides easily and in large amounts.